Ion/Molecule Reactions in Gaseous Isopropyl Alcohol

Article abstract of DOI:10.1246/bcsj.60.2727

The ion/molecule reactions observed in 4 Torr CH4 containing known small amounts of i-C3H7OH or i-C3H7OH/H2O mixture were studied over the temperature range 40-400 deg C.The experiments were carried out using a pulsed electron beam mass spectrometer.At low temperatures (<150 deg C), the major ions are i-C3H7OH2⁺(i-C3H7OH)n.By increasing the temperature, slow growth of ions m/z = 59, 85, and 101 is observed.These ions are assigned to (CH3)2COH⁺, (CH3)2CHC⁺(CH3)2, and C6H13O⁺, respectively.They are probably produced from reactions of i-C3H7⁺ with isopropyl alcohol.The (CH3)2COH⁺ ion may be produced from the electrophilic attack of i-C3H7⁺ onto the secondary carbon atom of i-C3H7OH.At high temperatures (ca. 400 deg C), the (CH3)2COH⁺ ion becomes dominant.Acid-catalyzed dehydration of isopropyl alcohol, i-C3H7OH⁺ + H2O --> H3O⁺(H2O) + C3H6, is also observed.Ion/molecule reactions involved in the present experiment are discussed according to the frontier-orbital theory.